appcrash in clr_failfast_80131623_presentationframework.dll!ms.internal.controls.webbrowserevent.documentcomplete

[SamBent]

[Port of a servicing fix in .NET 4.7-4.8]

Problem description:
WPF applications intermittently crashes in various parts of that application with an Invariant.Assert/Failfast when viewing documents with the WPF WebBrowser control in DocumentComplete.
The application is clearing IE by navigating to about:Blank as recommended by the IE team.
However, rarely, the DocumentComplete for the previous document occurs after navigating to about:blank, at which point WPF crashes the process.

Actual behavior:

Description: The application requested process termination through System.Environment.FailFast(string message).
Message: Unrecoverable system error.
Stack:
at System.Environment.FailFast(System.String)
at MS.Internal.Invariant.FailFast(System.String, System.String)
at MS.Internal.Controls.WebBrowserEvent.DocumentComplete(System.Object, System.Object ByRef)
at System.RuntimeMethodHandle.InvokeMethod(System.Object, System.Object[], System.Signature, Boolean)

[SamBent]

Fix ported to 3.1.19, 5.0.10, 6.0.